Glaze



Patented Apr. 27, 1937 UNITED STATES M O M W PATENT OFFICE GLAZE Henry M. Michel, Oakland, Calif., assignor of one-half to Edward M. Applegarth, Oakland,

No Drawing. Application May 31, 1932, Serial No. 614,633

1 Claim. (Cl. 13420) The invention relates to liquid preparations for coating walls and other surfaces.

In office buildings, hospitals and apartment houses and the like where there is a constant 5 change in tenancy, there arises the problem of frequently refinishing the walls. The repeated painting thus made necessary, however, causes the accumulation of paint coats which, as may be readily understood, forms a surface which tends to check, as well as to blister and to crack. On the other hand the difficulties and cost entailed in efiecting a removal of the coating are considerable. In instances where the walls are of plaster or the like, removal of the coating requires scraping of the plaster surface and a replastering thereof before recoating. For many years it had generally been the practise in ofiice buildings to use tint coating for the walls, but as the character and class of buildings became improved a more attractive finish was desired and the use of paint was reverted to. However, a painted surface, particularly a glossy one, has the disadvantage of accentuating any of the imperfections in the plaster. An attempt to im- 5 prove the foregoing led to the present practise of applying to the surface a thin colored glaze and then ragging or otherwise treating the wet glazed surface to produce a design not only surprisingly attractive but serving to hide the sur- 30 face imperfections. These finishes, however, when marred, faded or otherwise damaged by breaks in the plaster, may only be replaced by painting them out and reglazing. This latter procedure however leads again to the undesirable 35 accumulation of paint coats aforementioned.

With the foregoing in mind, applicant conceived and has produced a glazing liquid that can be put on an oil painted or similarly finished surface and removed therefrom at will without 40 affecting said surface, and which carries sufficient pigment or color whereby after ragging 1 or similar treatment, it serves to fully conceal any blemishes or imperfections in the plaster or any spots in the painted undercoat due to the 45 plaster having been repaired and painted over with a color intended to match the original.

Other features of my glaze are that it will hold what is termed in the paint trade as a wet edge, will dry with a hard surface, and will not 50 be aifected by a wet undercoat or water accidentally coming in contact therewith.

In the development of the invention it has been one of the objects to provide a glaze of the character described which could be prepared and 55 mixed in a simple and inexpensive manner.

Another object was to so proportion the amounts of the ingredients in the coating that the latter would remain in moist condition long enough to permit an even application of the coating over a comparatively large surface.

Still another object of the invention was to provide a coating of the character described wherein water is used instead of the customary oil or varnish thereby not only greatly decreasing the necessary cost of manufacture of the coating, but also establishing the same as a distinct product entirely separate from paint.

A further object was to provide a glaze of the character described which might be easily and effectively applied like paint and when dry would afi-ord a tough, smooth finish, would not chip or crack and would remain intact with an unbroken or unchecked surface over long periods of time without the necessity of recoating or retouching.

Yet another object has been to provide in a glaze of the character described a disinfectant agent operative in the event of dampness to prevent fermentation of the glaze or the formation of mold, as well as to be especially effective to prevent the coating from becoming a breeding place for infectious germs and therefore highly desirable for use in sanitariums and the like.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention. It is to be understood, however, that variations in the showing made by the said description may be adopted within the scope of the invention as set forth in the claim.

Briefly stated, the glaze of my invention is produced by converting a binder such as casein into momentary solution with an akali or ase, and then adding firstly a coa ulan TEE bring the solution to a colloidal swim secondly the pigments for yielding the desired color. The base here used is ammonium hydroxide which not only serves asm but owing to its unstable nature will completely evaporate on the drying of the coating whereby no alkaline residue will be left in the coating with which to cause a liquefying of the casein on the subsequent application of water to the coating. On the other hand, since the casein in the dry coating is still in such form as to readily dissolve in the presence of a basic solution, the subsequent application of say ammonium hydroxide to the coating will permit the ready and complete removal of the coating so as to leave the wall sur- Exam;

face in proper condition for an immediate recoating. In addition, a nonolatile acid or disinfectant is incorporated in the glaze to prevent ermentation of the casein when the latter is in the presence of moisture.

More specifically in the preferred embodiment of my invention I use a solution consisting of casein, ammonium hydroxide, silicate of soda, mo acid, pigmen an we er," a a xe as erema er se or to provide a liquid subject to application like paint or similar coatings and affording a homogeneous solution which when applied to a surface will neither run nor dry too, quickly, and which upon drying will deposit the binder and pigment on the surface in the form of a stable, elastic coat substantially insoluble in water.

The admixture of these ingredients may be effected in various ways. One method of combining the ingredients that has proven very satisfactory consists in separately mixing two groups of the ingredients and then combining said groups. For example, to mix a gallon of g laze, 14 ounces of finely powdered casein and 4 ounce of salicyIic'acid areadded to?! of a gallon of watenheated to 140 degrees F. The mixture is stirred well 'until no lumps remain and then 6 ounces of strong commercial ammoniumhydrgx; ide are stirred in until the mixture is homogene- 0115. Apart from this first portion, 7 112 c. c. of commercial'solution'of silicate of soda is mixed with one pint of water aridtlie resulting solution stirred into the mixtureof the first group. There is then added sufficient water to bring the total volume up to one gallon. Thereafter the admixture is stirred occasionally to prevent complete coagulation, and after about three days suitable pigments, preferably of an alkali-proof nature, may 'be' stirred into the epmuannmn the desired shade of color is obtained. Care should be exercised to avoid a surplus of pigment as the resultant product when dry will powder and impair the washability of the coating.

The advantageous qualities of the coating of my "invention as hereinbefore referred to are obtained as a combination of the various characteristics of ingredients used. The casein supplies the body of the preparation and. to a large extent gives the latterrits adhesiveness and elasticity and forms the binder between the pigment and the surface to which the coating applied. As casein is soluble in most dilute bases it first appeared that many of such bases could be used in mixing the coating. In most. instances, however, it was found that these bases on drying would precipitate a salt which upon being wetted would again give a basic; reaction and thereby dissolve the casein. In the absence of a binder, the pigment would then wash off. The coating produced therefore in the use of such bases, while presentingbther desirable characteristics, could not be washed or wiped with water. To obviate this shortcoming I conceived the idea of using a basic solution for mixing the preparation which upon drying would not leave a salt of'the character described. It is therefore with particular stress that I specify the use of ammonium hydroxide. This base while effective in dissolving caseimis an unstable chemical compound with the ammonium hydroxide in equilibrium with water and ammonia as. Consequently this base on drying simply gives off water vapor and amaforesaid does not contain any alkaline residue, except the small alkalinity due to the silicate of soda which is not sufficient to make the casein completely soluble, it will be clear that the coating when dry presents a surface on which water has slight effect unless applied with undue force and for a considerable period of time.

To the proper functioning of the glaze, the use of a substance such as silicaegfsoda is of considerable importance since it acts as afcoagulant to build up a colloidal state in the admixture which gives the liquid sufficient tenacity when applied to a surface to allow the wet surface to be ragged, that is, marked or embossed by partial wiping with a cloth, brush or the like, or otherwise finished, without danger of the liquid running and thereby spoiling the desired ornamental effect. The silicate of soda also functions when the coating is dry to increase the adhesiveness of the binder.

The salicylic acid used in the composition serves as an antiseptic'agent and while comprising about two percent of the solution prior to drying, forms a much larger proportion of the dry coating since in contrast to other ingredients it is non-volatile. This presence of the acid serves to prevent, in case of subsequent dampness, any fermentation of the preparation and moulding of the structure to which the coating is applied. The acid is particularly appropriate as it. is odorless, and so efieetively non-volatile as to permanently prevent any decomposition odor or the coating from becoming a breeding place for germs.

Attention is also directed to the abundance of water used. This not only affords an inexpensive carrier but insures a sufliciently slow evaporation or drying to enable the covering of a; large surface.

A highly desirable characteristic of my coating is that while it provides a substantially permanent and washable finish it is at the same time readily removable as aforesaid at the will of the user without in any way disturbing the sub-surface whether same be of oil paint or other material. As the binder for holding the pigment on the surface consists of casein, it will be clear that to effect a removal of such pigment, it is only necessary to dissolve the casein binder so as to permit the entire product to be readily washed away. As previously noted, the casein may, be readily dissolved in a dilute solution of most bases and therefore any of these bases may serve as a remover for the coating. Preferably, however, ammonium hydroxide, obtainable in the trade in a number of harmless household forms, or a solution readily prepared by adding from 3 to percent by volume of commercial ammonium hydroxide to water, is recommended as a remover ,in preference to other bases, as the ammonium hydroxide will dry without leaving an undesirable mediately recoated and treated for ornamentation as aforesaid, if desired.

I claim:

A glaze for painting wall surfaces or the like comprising a water admixture including casein arranged for depositing on a surface to be glazed,

ammonium hydroxide serving to maintain said casein in soluble form prior to application of monia gas and leaves no residue whatsoever. As th glaze and evaporating upon applieationoof the casein of its'elf'is not soluble in water, and as my coating when prepared in the manner the glaze in a manner depositing said casein on said surface, and silicate of soda coagulating said I06. COMPOSITIONS,

COATING OR PLASTIC.

glaze and holding the latter against running when applied to said surface, said ammonium hydroxide being substantially the sole basic substance in the glaze whereby upon evaporation 5 of the ammonium hydroxide said casein will be left substantially insoluble when washed with water yet readily soluble and removable upon HENRY M. IIJICHEL. 

